In window units which are intended for inserting into a predefined opening of motor vehicles and such like and have a window and a peripheral frame integrally formed thereon, it is sometimes the case that add-on parts, for example trim strips and such like, are fitted on the frame. Provided for this purpose on the relevant length section of the frame are a number of retaining devices by way of which the add-on parts are releasably connected, i.e. generally latched in by means of corresponding moldings in the manner of a snap-action closure.
Since the frame is in the form of an injection molding and is produced from more or less compliant material, the add-on part is not connected to the frame directly. In order to improve the latching connection, in the case of the retaining devices, use is made of a metal retaining clips [sic] which is positioned on a retaining strip on the frame, which, for its part, is integrally formed on the frame.
The retaining clips have an elongate, planar basic body, on the two longitudinal sides of which there are generally arranged two latching wings and three retaining wings, which follow one another alternately. The latching wings extend further outwards than the retaining wings and are designed such that, along with coordinated profile sections of the add-on part, they produce a latching connection.
The retaining wings have at least more or less a U-shaped vertical projection with legs of different lengths. The longer leg of the U-profile, which adjoins the basic body, forms a rear section, and the web part of the U-profile, as a side section, adjoins said rear section in the direction of the frame. The shorter leg of the U-profile is aligned inward, as a retaining section.
On the two remote sides, which run parallel to the longitudinal extent of the frame section, the retaining strips on the frame have in each case one retaining groove which is coordinated with the retaining section of the retaining wings. The retaining clip is pushed onto the retaining strip from the end side such that the retaining sections of the retaining wings thereof engage in the retaining grooves of the retaining strips. At a later stage, the add-on part is positioned on the retaining strips and pressed on until it has latched in on the latching wings.
On the retaining strips, the retaining grooves can only be produced with a very limited groove depth because it is necessary to demold the frame profile with the retaining strips following the injection-molding operation with the retaining-strip profile section located above the retaining grooves being elastically deformed in the process. This means that the retaining force for securing the retaining clips is also limited.
In order to achieve greater groove depth, the injection mold would have to operate with slide bars. This would result in very complex and expensive injection molds. Moreover, this would result in the problem of the slide bars having to be sealed very well in order that the comparatively low-viscosity material of the frame, during the injection-molding operation, does not penetrate into the interspaces between the slide bar and the slide-bar guide and makes the guide sluggish and, after a short period of time, even unusable. A further disadvantage of the slide bars would also be that the slide bars would have to be designed to be very small in comparison with the injection mold itself. This would mean that they would be very susceptible to malfunctioning.
With injection molds which operate without slide bars, it is possible to achieve groove depths which, if PVC is used as the frame material, result in retaining forces for the retaining clips, and thus for the add-on parts, which are just sufficient. If, for example, thermoplastic elastomers (TPE) are used as the frame material, the profile of the retaining strips is too compliant in order to produce a sufficient retaining force for the retaining clips. This means that the add-on parts may drop off even in the event of slight contact. If this happens a number of times and the retaining clips have to be repositioned on the retaining strips again and again, the profile section of the retaining strips against which the retaining section of the retaining wings of the retaining clips butt is subjected to wear to such a pronounced extent that the retaining clip is no longer secured at all.
The object of the invention is to provide a window unit, with an integrally formed frame and with retaining devices for an add-on part, in which the frame can be produced from a comparatively compliant material and a sufficient retaining force for the add-on part is nevertheless achieved. This object is achieved by a window unit having the features specified in claim 1.
Since each retaining strip is formed by an insert body, on which the frame is integrally formed in the injection mold as it is on the window, and since the material of the insert bodies is of a higher strength than the material of the frame, it is possible to achieve sufficient retaining forces for the add-on part even with a comparatively compliant frame material.
Since the insert bodies are prefabricated as individual parts in a dedicated injection mold, in which the operation of demolding can be carried out differently than that in the injection mold for the frame, the retaining grooves may be produced with a greater groove depth than has otherwise been the case, which, in conjunction with the higher dimensional stability of the material of the insert bodies, increases the retaining force for the retaining clip and thus for the add-on part.
By virtue of the configuration according to claim 2, the insert bodies, on the one hand, have a high dimensional stability and, on the other hand, undergo good bonding with a TPE frame material.
By virtue of the configuration according to claim 3, the underside of the insert body is kept at a certain distance from the window, with the result that the frame material can also penetrate inbetween the underside of the insert body and the window and can thus bond the insert body to the window to even better effect.
By virtue of the configuration according to claim 4, the insert body can be positioned very precisely in the injection mold for the frame and fixed for the injection-molding operation of the frame. Moreover, the positioning stubs or positioning strips may serve as spacer elements in relation to the window. In a development according to claim 5, those parts of the positioning stubs or positioning strips which project beyond the outline of the frame can easily be removed once the window unit [sic] has been demolded, with the result that they do not cause any disruption when the window unit is mounted at the envisaged use location.
By virtue of the configuration according to claim 6, the retaining clips can be positioned and fixed very well on the retaining strips. A development according to claim 7 makes it easier for the retaining clips to be pushed onto the retaining strips.